Radial diffusion compressors



June 14, 1960 E. A. STALKER RADIAL DIFFUSION COMPRESSORS Filed Jan. 31, 1952 IN V EN TOR.

2,94%,659 Patented June 14, 1960 RADIAL DIFFUSION COMPRESSORS Edward A. Stalker, 436 N. Farragut St., Bay City, Mich.

Filed Jan. 31, 1952, Ser. No. 269,238

6 Ciaims. (Cl. 230-120) This invention relates particularly to radial diffusion compressors having a peripheral or tangential discharge.

An object of the invention is to provide an efiicient compressor capable of a high pressure rise per stage.

Another object is to provide a compressor utilizing radial diffusion which can efliciently discharge fluid in an outward or tangential direction.

The above objects are accomplished by the means illustrated in the accompanying drawings in which- Fig. l is an axial section through a compressor according to this invention;

Fig. 2 is a front view of armor of this invention;

Fig. 3 is a fragmentary development. of. the bladingof the rotor; and

Fig. 4 is a rear view of the compressor of Fig. 1.

In one form of the compressor. of this inventionfluid is diffused in the radial direction in a passage having .a generally axial direction of increasing radial depth and directed from the rotor with an axial component of velocity small relative to the peripheral component.

Referring now to the drawings the compressor isindicated generally as 10. It is comprised of the bladed rotor 12 mounted for rotation in the bearings 14' and 15. The rotor has the peripherally spaced blades 20 about the hub 22 defining the passages 24 therebetween. These passages have their inlets 26 at the front and their exits 28 at the rear of the rotor to discharge fluid from the rotor in the general axial direction relative to the rotor.

The hub increases in diameter rearwardand the blades are substantially sealed to the hub along amajor portion of the length of the blade to facilitate the attainment of a substantial pressure rise in the pumped fluid.

The case 16 is comprised of the rotor housing 30 and the case portion or collector 32. The inlet to the compressor is 34.

Each rotor passage increases in radial depth and cross sectional area along the forward portion 40 and decreases in radial depth along the rearward portion 42 while maintaining the cross sectional area substantially constant. This is accomplished by curving the blades along the chordwise direction, that is, chordwise toward the direction of rotation along the rear portion of the passage. Due to the curvature and the. originalpositive pitch angle 6 Fig. 3 of the blades the cross sectional width between the blades increases along the rear portion of the passage permitting a reduction of the radial depth for the same cross sectional area as the rear of the forward portion of the passage. The pitch angle of the blades is also the pitch angle of each passage.

The radial increase in depth preferablyresults inzalarge ratio of the cross sectional area at the exit to the cross sectional area at the inlet to each rotor passage. Aprefer-red value for moderate peripheralspeeds is from about 2 to about 4.

The maximum angle of diffusion-D between the outer wall bounding the rotor passages (such as housing '30) and the peripheral surface of the hub 22- can be very large because centrifugal pressure will keep the flow againstthe outer wall and preclude separation therefrom. Also at the hub theincrease in the pressure outward from the hub will keep the flow from separating therefrom. Values of D as high as 60 may be used efliciently although for most purposes the prefererd. range is from 15 to 4S.

It is important to difiuse the fluid in the rotor passages rapidly so as to keep the axial length of the rotor to a small dimension. The rotor length may be kept to a value comparable to the maximum radial depth. of the rotor passages. Thus the axial. length can be less. than half the tip diameter of the blades.

By making the diffusion ratio of large value the axial velocity of the fluid relative to the rotor is small. By curving the blades in the direction of rotation the fluid is given a high peripheral velocity so that the direction of the fluid flow from the rotor relative .to the case is very close. to the. plane of rotation. This improves the efiiciency with which the collector 32 can operate incollecting the fluid and discharging it out the discharge duct 50 which directs thefluid outward transversely to the, rotor exits.

In .Fig. 3 the. axial velocity relative to the rotor is 52 and the peripheral velocity is 54 giving a resultant or absolute velocity 56 whichmakes a very fiat angle with theplaneof rotation.

Another advantage of curving the blades is that theexit has shorter radial depth so that there is. less difference in peripheral velocity radially across the flow. Also the average peripheral velocity imparted to the fluid is higher.

Preferably the forward portion 40 of each rotor. pas- ,sagesis substantially straight withtheaft portions curved along the chordwise preferably toward the direction of rotation. However a small amount of curvature can be used in the forward portion. Also the cross sectional areas of thepassages 24-may increase somewhat rearward along the aft portions of the passages but the rateiof increase of. cross sectional area along the aft portion should be substantially less than along the forward portion. If there were a substantial increaseincross sectional. areasthe flow would separate from the. aft portions ofthe blades. Preferably the cross sectional areas should be about constant along the aftportions.

The machine. of this inventionis useful in pumpingall types of fluid.

I claim:

1. In combination in a compressor, a case, and a rotor mounted insaid case for rotation about an axis, said rotor havingsurfaces including peripherally and radially directed surfacesdefining a passage therethrough from aninlet at thefront thereof to auexit at the rear thereof facing in the general axial direction, said case cooperating with said rotorv to guide a flow of fluid through said passage, said radial surfaces varying in radial depth providing each said passage incooperation with said peripheral surface with substantially increasing radial depth and crosssectional area rearward along the forward portion thereof and decreasing. radial depthrearward along the aft portion thereof defining a maximum cross sectional area. intermediate said inlet and exit, the. portions of said radially directed surfaces which in part definesaid aft portionof said passage being curved rearward along the chord direction toward the direction of rotation, therearwardportions .ofsaid peripheral surface being positioned successively further out radially relative to said case and cooperating therewithand with said radial surfaces to provide a. cross. sectional area adjacent the exit of said passage lessthan said maximum cross sectional area and greater thanthe cross sectional. area-v at said inlet, said case having a portion adjacent the rear of said rotor adapted to receive fluid axially thereinto from said'passage and having a discharge duct directing the fluid outwardly transverselyto said axis. I V e 2. t. In comb ination 'in'a machine for pumping flu d, a case, and a rotor mounted in said case for rotatlon about an axis, said rotor having a rotor hub and a plurality of r 1 blades peripherally spaced thereabout defining a plurality of rotor flow passages between said blades, said case fitting closely to the tips of said blades along the lengths thereof and defining an outer boundary for each sa1d passage, each said passage having its inlet at the front side of said rotor and itsexit at the rear side facing in the general axial direction to discharge fluid therefrom rearward with'a velocity component in the direction of said axis, eachsaid' blade cooperating with said case and hub to. give each said passage increasing radial depth and'c ross sectional area rearward along its front portion and decreasing radial depth rearward along its rear portion defining a maximum cross sectional area at the rear ,end of 'asid forward portion, said blades being set at a positive pitch angle and curved chordwise rearward along their aft portions toward the direction of rotation progressively increasing the cross sectional width of each said passage rearward along its rear. portion, the portion of saidcase opposite said curved aft portions of each blade cooperating with said rotor hub and said blades to define cross sectional areas adjacent. said exits less than said a maximum cross sectional areas of said forward portions of said passages, said case having a portion adjacent the rear of said, rotor to receivesaid -fluid therefrom; said case'portion having adischarge duct directed transversely to said axis for directing said fluid outwardly transversely to saidaxis.

' 3. In combination in a compressor, a case, and a rotor hub mounted in said case for rotation about an axis, a plurality of blades can'iedon said rotor hub spaced peripherally thereabout defining with said hub and case a plurality of'rotor passages extending-from aninlet at the front to, an'exit at the rear of said hub facing in the forward portion thereof, to a maximum cross sectional area intermediate said inlet and exit in cooperation with said hub and case, the aft portion-of said hub increasingin diameter rearward along the aft portions 'of said blades' thereby decreasing in cooperation with said blades and said case the; radial depths and cross sectional areas of each said passage relative to said maximum-cross sectional area of said forward portion, said blades along their aft portions being curved toward the direction of rotor rotation and cooperating with said case and rotor hub to direct diameter rearward along substantial axial lengths of said aft portions of said blades and cooperating with said 'case and said aft portions of said blades to decrease the cross sectional areas and radial depthsof said passages rearward along said aft portions, said rotor hub along a substantial axial length of said rear portions having substantially greater diameters than at said inlets of said passages. a

5. In combination. in an axial flow pumpingmachine for increasing the pressure of a fluid, a case, a rotor hub structure mounted in said case for rotation about an axis, and a plurality of axial flow blades carried on said rotor hub structure spaced peripherally thereabout, said rotor hub structure having a substantial diameter in relation to the radial extent of the blades and being substantially coextensive in axial length therewith, said blades defining a plurality of axial flow passages therebetween with inlets and exits respectively at front and rear thereof, said exits facing rearward in the general axial direction and with rearwardly increasing cross sectional areas along the forward portions rearwardly from said inlets, the rearward portion of said hub structure increasing in diameter rearward therealong reducing the radial depth of each said blade and said passage'along the rear portions thereof in cooperation with said case, said 'bla'des' being i set at a positive angle of incidence and having-their aft said fluid from'said exits of said passages at a flatangle 'relative to the plane of said rotor rotation and chiefly transverse to said axis, said case having a portion adjacent the'rear of said rotor adapted to receive said fluid 'from'said passages for flow therein transversely to said axis, said case portionhaving a discharge duct for dis charging said fluid outwardly transversely to said axis. 7

' combination in a compressor, a case, a rotor hub mounted for rotation in said case, and a plurality of peripherally spaced blades carried on said rotor hub and having their trailing edges extending radially, said blades said blade having a foreportion 'of increasin'g'radial depth rearward therealong succeeded by an aft portion curved rear-ward along the chord 'directiontoward the direction of rotation, said rotor hub extending along and increasing portions curved rearward along the chord direction-toward the direction of rotation defining increasing cross sectional widths rearwardly along the rearward portions thereof and a cross sectional area at the exit of each said passage greater than at theinlet' thereof to direct said fluid of said rear passage portions having saidincreased width,

said case having a portion adjacent the rear of said rotor to receive said fluid from' said passagesfor flow therein ftran'sversely to said axis, said case portion' having a discharge'duct for discharging said fluid outwardly trans versely to said axis. 7 6. In combination in an axial flow pumping machine for increasing the pressure of a fluid, a case, a hub structure mounted in said'c'ase for rotation about an axis, and a plurality of axial flow blades carried on said hub structure spaced peripherally thereabout, said hub structure having a substantial diameter in relation to the radial extent of the blades and being substantially coextensive in axiallength-therewith, said blades defining a plurality of axial'lflow passages therebetween with inlets and exits facing in the general axial direction, the forward portions of said case and said hub structure in cooperation with said blades defining increasing cross sectional areas rearward along the forward portions of said flow passages, the rearward portion of said hub structure and said case relatively converging rearward therealong reducing the radialdepth of each said passagealong the rear portion thereof, said blades being set at a positive angle'of incidence and having their'rear portions curved rearward along the chord direction toward the direction of rotation, said curved rear blade portions and said converging hub and case cooperating to provide rearwardly decreasing cross sectional areas of said flow passages over the rearward portions, thereof 'with the cross sectionalarea at the exit :of each said passage being greater than at the inlet thereof to direct said fluid from said exit-s of said passages at a flat angle relative to the'plane of rotor rotation" and chiefly transversely to said axis, said case having a portion adjacent-the rear of said rotor to receive said fluid from said passages for flow therein transversely to said axis,said case portion having a discharge jduct for discharging said fluid outwardly"transversely to' said axis.

(References on following page) References Ciiefi in the file of this patent 2,483,335 UNITED STATES PATENTS 2,628,768

1,153,872 Matsler Sept. 14, 1915 2,016,831 Havill Oct. 8, 1935 5 242,692 2,371,706 Planiol Mar. 20, 1945 688,409

6 Davis Sept. 27, 1949 Kantrowitz Feb. 17, 1953 FOREIGN PATENTS Switzerland May 31, 1946 France May 12, 1930 

